It’s no secret, I’m VIM fan. Any time I have to take my hands off the keyboard to mess with a GUI I have issues.
My palms get all sweaty, I break out in hives, and have a vague feeling like I’m playing a game of whack-a-mole.
Well, it may not be that bad, but I’m sick of it. So I decided to do something about it.

I split my time almost equally been my editor and my browser, why not use the same keyboard shortcuts?
Enter Vimium, a customizable Google Chrome extension that gives you vim-like control over your browser.
All the commands are spot on, G and gg scroll you to the bottom or top of the page, respectively.
Hitting f will display a character next to all the links on a page, hitting that letter opens the associated link.
A quick gs will allow you to view source, easier to remember than opt+cmd+U (Ctrl+U on windows, lucky bastards.)
Even marks work as expected!

So now I can browse without the cursor, how can I manage windows?
Cmd+tab is woefully under-powered, and windows has Aero; why not improve both?
Slate does just that by offering custom configuration and tons of options.
By default Slate is easy to use, but via custom configuration
you can tweak your way to the perfect environment. I’ve done everything I could come up with to
my Slate config to make it work more
like vim, and it’s fantastic! (I stole a lot from other’s configs, that’s the beauty of config files and sharing)
With my config Cmd+ctrl+E (default is Cmd+esc) will show a character for each open window, even if they’re hidden behind others.
Cmd+ctrl+[hjkl] uses the standard vim keys for placing a window on the half of the screen indicated by the direction (default are arrow keys, IIRC).

Even better, they’re BOTH free, open-source, and (the icing on the cake) hosted on github; so you can inspect the code at your leisure.

UPDATE
As of August 2016, Slate hasn’t been updated in 4 years, despair not, there is an updated fork at mattr-slate
that can be installed with homebrew via brew cask install mattr-slate